fix(session): recover concatenated session index records

[shizhigu]

Related Issue

Resolve #1925

Problem

If two session_index.jsonl records lose their newline separator, the reader drops both as invalid JSON. The session directory remains intact, but resume returns session.not_found.

The writer-side trigger is still unknown, so this change is limited to read-time recovery.

What changed

• Keep JSON.parse as the single-record fast path. On failure, scan adjacent JSON containers with correct nesting, string, and escape handling.
• Apply complete records in file order through the existing path checks. Stop at malformed data, then continue with the next physical line.
• Put the v2 compatibility reader behind a private App-scoped Store. Workspace services consume validated entries and no longer know about bytes or JSONL framing.

flowchart LR
  I[session_index.jsonl] --> V1[v1 SessionStore reader]
  I --> S[v2 legacy-index Store]
  S --> W[Workspace services]

Loading

Here A and B are complete records:

Input	Recovered
A\nB	A, B
AB	A, B
A + truncated B	A
A + garbage + B	A

Recovery does not rewrite the index.

Validation

• v1: 31 focused and 3,983 full-suite tests passed.
• v2: 33 focused and 3,960 full-suite tests passed, including a 150,000-record line.
• Public SDK resume regression: 8 passed, 1 todo. Full node-sdk suite: 231 passed, 1 todo.
• Three package typechecks, v2 domain lint, type-aware lint, klient smoke, changeset status, and git diff --check passed.

The original Windows writer-side trigger was not reproduced. Tests use the missing-separator shape from the issue.

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue, or explained the problem above.
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

[changeset-bot]

🦋 Changeset detected

Latest commit: 8770228

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@moonshot-ai/kimi-code	Patch

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